This seems to be now marked as a "repeat" but a couple of Guides that I look at don't agree.
If you recall that the last episode of the previous series was called "The Reichenbach Fall", and if you're familiar with the original Sherlock Holmes stories, you should know what's likely to have happened (in broad terms) to Sherlock. That may prompt your memory of whether you've seen this next (and most recent) series of Sherlock.
The Ghost Sherlock of Seasons Past has been raised again: the episode of Sherlock on tonight (Thu 4 Feb) is a repeat.
It must have been updated because the recording had an [R] at the end for me. I was surprised to see it as earlier in the evening it was not in the entry on the timer listing on my 7100+.